The invention relates first of all to a method for treating open cut edges of a packaging sleeve, a blank or a web material of a packaging material, rolled up into a roll, in particular of a cardboard/plastics composite material, by applying or introducing a disinfectant-containing treatment agent to or into the outer region of the cut edges.
The invention also relates to a correspondingly sterilised packaging material for the production of a packaging, in particular of a beverage carton, substantially consisting of a composite material with a pulp/cardboard layer, to a composite packaging produced therefrom and to suitable containers for receiving packaging material.
When the expression “open cut edges” is used in the following, it means not only the cut edges which delimit a blank or a packaging sleeve formed therefrom, but also all “open” pulp regions which are exposable to the surrounding atmosphere, so that in particular cut edges inside perforations are also meant, as are found in beverage packagings in the region of pouring elements to be applied or other opening aids.
Cardboard/plastics composite packagings are either produced in the so-called “tubular forming process” from a roll or are produced from individual blanks of paper/plastics laminate material. Here, individual blanks are initially obtained from a roll of composite material and are then provided with a tight longitudinal seam which is generally produced by folding and sealing the composite material and, if appropriate, by additionally overbonding with a sealing strip.
The further processing of packaging sleeves produced in this manner, i.e. the unilateral closure at the top or bottom of the subsequent packaging, sterilisation, filling and re-closure is generally performed directly in the filling machine.
The steps of cup formation, cleaning and, if appropriate, disinfection are carried out here before the filling material is poured in and the composite packaging is closed and finally shaped. During production of a so-called aseptic composite packaging, the disinfection and filling procedures are carried out in the aseptic zone of a filling machine. If the cup is formed before the disinfection or sterilisation step, it can also be formed outside the aseptic zone. Methods of this type are described, inter alia, in DE 32 35 476 A1 and in DE 10 2009 029 706 A1.
Irrespective of the production method, the packaging is usually closed by compressing and sealing the edges of the packaging material, for example, by ultrasound using a sonotrode and an anvil. Other methods for closing the packaging are also known, for example electromagnetic induction or charging with hot air in conjunction with mechanical pressing.
It has been found that dust in particular is responsible for bacterial contamination, so that the primary objective of all steps should be to avoid dust. This can be carried out by the suction-removal of dust during production of the packaging sleeve and by reducing the lifetime of the cutting blades which are used. However, due to the fibres in the pulp of the cardboard which is used, the open cut edges always remain the “problem areas” in the production of the packaging. Although in most cases, efficient suction installations are helpful here, the high energy costs and noise emissions thereof put a strain on the production process.
An “aseptic packaging” is understood as meaning a packaging into which a filling material, particularly a foodstuff, is filled under aseptic conditions. Filling machines used for this purpose comprise an aseptic zone, a type of clean room, in which sterile, i.e. germfree conditions prevail and which is generally maintained by the closed or substantially closed configuration thereof, except for a few openings. The clean room atmosphere created therein is also under overpressure due to the introduction of sterile air, thereby preventing the entry of germs from outside. The packaging material is then transported continuously or discontinuously through the aseptic zone, being successively sterilised, dried and filled and closed in one or more steps. Contemporary prior art machines, for example a machine from the 24 series by the Applicant, allow per processing step a processing time of an individual sterilisation or filling station of approximately 0.6 seconds to approximately 0.85 seconds, subject to the packaging format.
The edges of packaging sleeves are open cut edges of an otherwise water-tight laminate material which may also have an oxygen barrier. Therefore, the risk of bacterial exchange (microorganisms and spores) exists primarily in the region of the edges, as a result of which the bacterial load of the material can increase and ultimately contamination of the product cannot be ruled out either during the subsequent filling procedure of the packaging or during the closing procedure for producing the finished packaging.
Closing a unilaterally open, full container consisting of composite material entails the risk that if the material is sealed by ultrasound in particular, dust from the packaging material can be projected out of the open cut edges and can contaminate both the aseptic region of the filling machine and the open packaging itself.
Single-cell organisms which are capable of replication by cell division and which can replicate in the filling material (“product”) of a packaging and, in so doing, are capable of altering the characteristics of the filling material are understood as vegetative microorganisms. The term also includes the survival forms of the replication-competent single-cell organisms, such as the spores thereof.
These spores are generally very resistant to changes in the environmental conditions surrounding them. If microorganisms do not find an environment for metabolism and/or multiplication, some microorganisms can be converted into a spore stage.
More precisely, in the context of the present application, the term “microorganisms” is understood as meaning eukaryotes and prokaryotes, eukaryotes having a true cell wall and comprising algae, protozoans, fungi and slime mould, while prokaryotes cover the group of bacteria (cf. “Bergey's Manual of Determinative Bacteriology”, 8th Edition, Baltimore: Williams & Wilkins, 1974).
Survival forms such as spores are known specifically in the case of prokaryotes. For example, even after the thermal and/or chemical treatments of raw materials for the production of raw cardboard products, spores can be found to an increasing extent precisely in these products, since treatment methods of this type either kill off the directly replication-competent form of the microorganisms or initiate conversion into the spore form.
The expression “colony-forming unit per gram” (CFU/g) is known to a person skilled in the art as an indication of the number or quantity of microorganisms contained in an amount of substance (for example in the raw cardboard product mentioned). Unlike the direct counting of all present microorganisms using a suitable optical means, the number of colony-forming units is determined by the deliberate reproduction of dividable microorganisms which are present under suitable cultivation conditions. This is generally carried out up to a colony size which can be counted by unmagnified vision. In this respect, use is made of the fact that precisely one colony is produced from each individual dividable microorganism under previously defined conditions. Individual cases in which two CFU are positioned so closely together that only one visible colony is formed therefrom are then routinely disregarded.
Determination methods which are typical in microbiology are regulated by ISO 8784-1 from 2005.
Thus, a reduction in the CFU/g is used by a person skilled in the art as an indication of the efficiency of a method for bacteria reduction and is often called the disinfection rate. Derived therefrom is the sterility rate to be counted via the number of produced packagings.
It is known from DE 10 2011 111 523 A1 to treat cut edges, open at the top or bottom, of a packaging sleeve of a packaging material by applying a treatment agent which contains a disinfectant, the disinfectant remaining on the cut edges after application and penetrating inside the packaging material. The treatment agent is respectively applied by being sprayed from above, a plurality of packaging sleeves being combined in a folded-flat state. In this known method, the treatment agent is applied to the edges of the packaging sleeve in a station, constructed specifically for this purpose, in one or more separate method steps immediately before the packaging sleeves are packed into a covering box. This approach is relatively complex. There is also the risk that the treatment agent will be accidentally sprayed beyond the packaging. Additionally, it has been found that the outsides of the packaging sleeves can quickly be affected. For example, the treatment agent can act in an undesirable manner on the printed image on the outside of the packaging sleeve and can damage it. It can also happen that two packaging sleeves remain stuck to one another after being removed from the covering box and can disrupt production during their further processing in the filling machine.
On this basis, the object of the invention is to provide a particularly resource-efficient composite packaging and a production method required for this purpose.